GB2105749A - Plating articles - Google Patents

Abstract

In a method of selectively plating articles, particularly plating metal electrical contacts with a precious metal over their contact areas, the articles are plated over substantially their entire surface areas and then the selected areas are masked and the plating is removed from the remaining areas, the removed plating material being recovered for re-use. In the case of pin contacts, the contact area 16 of the pin portion 10 may be masked by the application of a sleeve 18: in the case of a socket contact, the internal contact area thereof may be masked by inserting a pin so as to become embraced by that area of the socket. <IMAGE>

Description

SPECIFICATION Plating articles This invention relates to a method of plating articles, particularly but not solely loose articles, over selected areas. The invention has particular but not exclusive application to plating electrical contacts with gold or other precious metal.

In the particular case of electrical contacts, for example pins and sockets especially for multi pinand-socket connectors, it is known to plate each contact with gold over a selected area (being the area which is to physically and electrically mate with another contact) or at least to plate a selected area to a greater thickness than over the remaining areas. It is a waste of the gold or other precious metal if areas which do not require the gold plating are plated nonetheless, or are plated to greater than a required thickness: in the case of socket contacts particularly, it is necessary to plate the entire contact to a considerable thickness to ensure that the internal socket surfaces receive a plating of sufficient thickness.

In accordance with this invention, there is provided a method of selectively plating articles, comprising plating the articles over substantially their entire surface areas and then masking selected areas and removing the plating from the remaining areas. In the case of gold or other precious metals particularly, the removed plating material should be recovered for reuse. Where the articles are loose metal articles, they may be electroplated in a barrel plating process: that is to say, the loose metal articles are contained in a rotating barrel formed of mesh or perforated material which is immersed in the electrolyte, the articles being connected to one pole of the electrical power supply by way of an immersed dangler or a stud contact attached to the barrel.

In the case of electrical contacts in the form of pins, once plated these may be masked by applying sleeves over the contact areas of the pins. In the case of electrical contacts in the form of sockets, once plated these may be masked by inserting pins which are thus embraced by the internal contact areas within the sockets.

Embodiments of this invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic longitudinal section through an electrical pin contact; and Figure 2 is a similar section through an electrical socket contact for mating with the pin contact of Figure 1.

Referring to Figure 1, a pin contact is formed from a solid metal blank (for example of a copper alloy) and comprises a cylindrical pin portion 10, an enlarged annuiar shoulder portion 12, and a cylindrical crimp bucket portion 14 (for receiving and crimping about an electrical conductor). The pin portion requires plating with gold over the cylindrical area 1 6 (which is to physically and electrically mate with the internal surface of a socket contact).

Referring to Figure 2, a socket contact is also formed from a solid metal blank and comprises a socket portion 20, an enlarged annular shoulder portion 22 and a cylindrical crimp bucket portion 24. In the initially cylindrical socket portion 22, two longitudinal slots are cut diametrically opposite each other and the two remaining portions are bent inwards to form a pair of spring fingers, as shown, for gripping a pin contact when inserted. The socket contact also includes a metal sleeve 26 applied (after the plating) over the socket portion. The socket contact requires plating with gold over the areas 28 of the socket spring fingers which areas are those which physically and electrically mate with the pin contacts when inserted.

In accordance with this invention, the loose electrical contacts are plated with gold in a barrel plating process. Prior to the gold plating, a preplating with (for example) copper then nickel may be carried out (also by barrel plating). After the gold plating, the selected areas are provided with a chemically resistant mask: in the case of the pin contact, the masking may be effected by coating with a resist, or by applying a sleeve 18, or by inserting the pins into a multi-aperture jig. In the case of the socket contact, masking may be effected coating with a resist or by inserting an appropriate pin into the socket with the effect of opening up the spring fingers for these to embrace the pin over the areas 28.One suitable resist is wax which may be applied by touching the socket onto the surface of molten wax so that surface tension draws the wax into the socket: eventual removal of the wax may be effected by washing with hot water.

Once masked, the contacts are immersed in an appropriate chemical solution to dissolve the exposed gold plating, tumbling the parts in a perforated barrel immersed in the solution being preferred. All of the solution is carefully saved and the gold is subsequently reclaimed from it. The contacts are then rinsed (again the solution being carefully saved for reclaiming the residual gold), and dried, and next the mask is removed. Finally, if required, the contacts may be provided with a thin plating of gold continuously over all surface areas, again by the barrel plating process.

In the case of the pin contacts, these may be fed automatically to a station at which masking sleeves (e.g. of plastics material) are automatically applied. Likewise, the socket contacts may be fed automatically to a station at which metal masking pins are automatically inserted. The masking sleeves or pins may be removed automatically after the gold plating.

Claims (Filed on 9/9/82) 1. A method of selectively plating articles, particularly electrical contacts, comprising plating the articles over substantially their entire surface areas and then masking selected areas and removing the plating from the remaining areas.

2. A method as claimed in claim 1, further comprising recovering the removed plating material for re-use thereof.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (9)

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Plating articles This invention relates to a method of plating articles, particularly but not solely loose articles, over selected areas. The invention has particular but not exclusive application to plating electrical contacts with gold or other precious metal. In the particular case of electrical contacts, for example pins and sockets especially for multi pinand-socket connectors, it is known to plate each contact with gold over a selected area (being the area which is to physically and electrically mate with another contact) or at least to plate a selected area to a greater thickness than over the remaining areas. It is a waste of the gold or other precious metal if areas which do not require the gold plating are plated nonetheless, or are plated to greater than a required thickness: in the case of socket contacts particularly, it is necessary to plate the entire contact to a considerable thickness to ensure that the internal socket surfaces receive a plating of sufficient thickness. In accordance with this invention, there is provided a method of selectively plating articles, comprising plating the articles over substantially their entire surface areas and then masking selected areas and removing the plating from the remaining areas. In the case of gold or other precious metals particularly, the removed plating material should be recovered for reuse. Where the articles are loose metal articles, they may be electroplated in a barrel plating process: that is to say, the loose metal articles are contained in a rotating barrel formed of mesh or perforated material which is immersed in the electrolyte, the articles being connected to one pole of the electrical power supply by way of an immersed dangler or a stud contact attached to the barrel. In the case of electrical contacts in the form of pins, once plated these may be masked by applying sleeves over the contact areas of the pins. In the case of electrical contacts in the form of sockets, once plated these may be masked by inserting pins which are thus embraced by the internal contact areas within the sockets. Embodiments of this invention will now be described, by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic longitudinal section through an electrical pin contact; and Figure 2 is a similar section through an electrical socket contact for mating with the pin contact of Figure 1. Referring to Figure 1, a pin contact is formed from a solid metal blank (for example of a copper alloy) and comprises a cylindrical pin portion 10, an enlarged annuiar shoulder portion 12, and a cylindrical crimp bucket portion 14 (for receiving and crimping about an electrical conductor). The pin portion requires plating with gold over the cylindrical area 1 6 (which is to physically and electrically mate with the internal surface of a socket contact). Referring to Figure 2, a socket contact is also formed from a solid metal blank and comprises a socket portion 20, an enlarged annular shoulder portion 22 and a cylindrical crimp bucket portion 24. In the initially cylindrical socket portion 22, two longitudinal slots are cut diametrically opposite each other and the two remaining portions are bent inwards to form a pair of spring fingers, as shown, for gripping a pin contact when inserted. The socket contact also includes a metal sleeve 26 applied (after the plating) over the socket portion. The socket contact requires plating with gold over the areas 28 of the socket spring fingers which areas are those which physically and electrically mate with the pin contacts when inserted. In accordance with this invention, the loose electrical contacts are plated with gold in a barrel plating process. Prior to the gold plating, a preplating with (for example) copper then nickel may be carried out (also by barrel plating). After the gold plating, the selected areas are provided with a chemically resistant mask: in the case of the pin contact, the masking may be effected by coating with a resist, or by applying a sleeve 18, or by inserting the pins into a multi-aperture jig. In the case of the socket contact, masking may be effected coating with a resist or by inserting an appropriate pin into the socket with the effect of opening up the spring fingers for these to embrace the pin over the areas 28.One suitable resist is wax which may be applied by touching the socket onto the surface of molten wax so that surface tension draws the wax into the socket: eventual removal of the wax may be effected by washing with hot water. Once masked, the contacts are immersed in an appropriate chemical solution to dissolve the exposed gold plating, tumbling the parts in a perforated barrel immersed in the solution being preferred. All of the solution is carefully saved and the gold is subsequently reclaimed from it. The contacts are then rinsed (again the solution being carefully saved for reclaiming the residual gold), and dried, and next the mask is removed. Finally, if required, the contacts may be provided with a thin plating of gold continuously over all surface areas, again by the barrel plating process. In the case of the pin contacts, these may be fed automatically to a station at which masking sleeves (e.g. of plastics material) are automatically applied. Likewise, the socket contacts may be fed automatically to a station at which metal masking pins are automatically inserted. The masking sleeves or pins may be removed automatically after the gold plating. Claims (Filed on 9/9/82)

1. A method of selectively plating articles, particularly electrical contacts, comprising plating the articles over substantially their entire surface areas and then masking selected areas and removing the plating from the remaining areas.

2. A method as claimed in claim 1, further comprising recovering the removed plating material for re-use thereof.

3. A method as claimed in claim 1 or 2, in which the plating material is a precious metal.

4. A method as claimed in any preceding claim, in which the articles are loose metal articles and the plating of these articles is carried out by electro-plating in a barrel plating process.

5. A method as claimed in any preceding claim, in which the articles are electrical pin contacts and the masking is carried out by applying sleeves over the contact areas of the pins.

6. A method as claimed in any one of claims 1 to 4, in which the articles are electrical pin contacts and the masking is carried out by inserting the pins into the apertures of a multiaperture jig.

7. A method as claimed in any one of claims 1 to 4, in which the articles are electrical socket contacts and the masking is carried out by inserting pins into the sockets so that these pins are thus embraced by the internal contact areas within the sockets.

8. A method as claimed in any one of claims 1 to 4, in which the articles are electrical socket contacts and the masking is carried out by touching the socket onto the surface of a resist material which is in liquid state, so that the resist material is drawn into the socket by surface tension effects whereafter it is allowed to solidify.

9. A method of selectively plating articles, substantially as herein described with reference to the accompanying drawings.